dagger2使用方法教程之简明讲解

@Qualifier
@Retention(RetentionPolicy.RUNTIME)
public @interface A {}

@Qualifier
@Retention(RetentionPolicy.RUNTIME)
public @interface B {}

@module
public class SimpleModule {
 @Provides
 @A
 Cooker provideCookerA(){
 return new Cooker("James","Espresso");
 }

 @Provides
 @B
 Cooker provideCookerB(){
 return new Cooker("Karry","Machiato");
 }
}

public class ComplexMaker implements CoffeeMaker {
 Cooker cookerA;
 Cooker cookerB;
 @Inject
 public ComplexMaker(@A Cooker cookerA,@B Cooker cookerB){
 this.cookerA = cookerA;
 this.cookerB = cookerB;
 }
}

@module
public class MainModule {
 @Provides
 @Named("red")
 public Cloth getRedCloth() {
 Cloth cloth = new Cloth();
 cloth.setColor("红色");
 return cloth;
 }

 @Provides
 @Named("blue")
 public Cloth getBlueCloth() {
 Cloth cloth = new Cloth();
 cloth.setColor("蓝色");
 return cloth;
 }

 @Provides
 public Clothes getClothes(@Named("blue") Cloth cloth){
 return new Clothes(cloth);
 }
}

public class MainActivity extends AppCompatActivity {
 ...
 @Inject
 @Named("red")
 Cloth redCloth;
 @Inject
 @Named("blue")
 Cloth blueCloth;
 @Override
 protected void onCreate(Bundle savedInstanceStatE) {
 ...
 tv.setText("我现在有" + redCloth + "和" + blueCloth );
 }
}

//PerActivity.java
@Scope
@Retention(RetentionPolicy.RUNTIME)
public @interface PerActivity {}

//Activitymodule.java
@module
public class Activitymodule {
 @Provides
 CoffeeShop provideCoffeeShop(){
 return CoffeeShop.geTinstance();//一个普通的单例
 }

 /**
 * 直接在这里说结果，@PerActivity是用@Scope注解的，除了在这里注解还需要在用到该Module类的Component的类名上方也要注解，然后该实例在注入到某个类里的时候用同一个Component就会不管有几个字段都会只有一个实例。注意：如果用不同的Component实例的话仍然会新的CookerFactory实例，单例CookerFactory只存在一个Component实例里。所以叫局部单例。
 */
 @Provides
 @PerActivity
 CookerFactory provideCookerFactory(){
 return new CookerFactory();
 }

 @Provides
 CookerFactorymulty provideCookerFactorymulty(){
 return new CookerFactorymulty();//非单例
 }
}

//CoffeeShop.java
public class CoffeeShop {
 private static CoffeeShop INSTANCE;
 private CoffeeShop(){
 Log.d("TAG","CoffeeShop New Instance");
 }

 public static CoffeeShop geTinstance(){
 if(INSTANCE == null){
 INSTANCE = new CoffeeShop();
 }
 return INSTANCE;
 }
}

//CookerFactory.java
public class CookerFactory {
 public CookerFactory(){
 Log.d("TAG","CookerFactory New Instance");
 }
}

//CookerFactorymulty.java
public class CookerFactorymulty {
 public CookerFactorymulty(){
 Log.d("TAG","CookerFactorymulty New Instance");
 }
}

//除了在Module的Provides方法里写上@Scope还需要在Component类名上方写上，这里自定义的@Scope名字叫PerActivity
@PerActivity
@Component(modules = {Activitymodule.class})
public interface ActivityComponent {
 void inject(MainActivity simpleActivity);
}

public class MainActivity extends Activity {
 ActivityComponent activityComponent;
 @Inject
 CoffeeShop coffeeShop1;

 @Inject
 CoffeeShop coffeeShop2;

 @Inject
 CookerFactory cookerFactory1;

 @Inject
 CookerFactory cookerFactory2;

 @Inject
 CookerFactorymulty cookerFactorymulty1;

 @Inject
 CookerFactorymulty cookerFactorymulty2;

 @Override
 protected void onCreate(Bundle savedInstanceStatE) {
 super.onCreate(savedInstanceStatE);
 setContentView(R.layout.activity_main);
 activityComponent = DaggerActivityComponent.builder()
 //下面这句话可以不写，因为Module有默认构造函数。如果Module的构造器里有参数，并且该参数不是注入进去的，就需要用类似下面的方法手动设置实例到Component中
 .activitymodule(provideModule())
 .applicationComponent(MyApplication.getComponent()).build();
 activityComponent.inject(this);
 coffeeFactory.run();
 }
 
 private Activitymodule provideModule(){
 return new Activitymodule();
 }
}

07-11 16:53:27.978 1927-1927/? D/TAGs CoffeeShop New Instance
07-11 16:53:27.978 1927-1927/? D/TAGs CookerFactory New Instance
07-11 16:53:27.978 1927-1927/? D/TAGs CookerFactorymulty New Instance
07-11 16:53:27.978 1927-1927/? D/TAGs CookerFactorymulty New Instance

//Person.java
public class Person {
}

//PerActivity.java
@Scope
@Retention(RetentionPolicy.RUNTIME)
public @interface PerActivity {}

//BaseModule.java
@module
public class BaseModule {

 @Singleton
 @Provides
 public Person providePerson(){
 return new Person();
 }
}

//Module1.java
@module
public class Module1 {

}

//Module2.java
@module
public class Module2 {

}

//BaseComponent.java
@Singleton
@Component(modules = BaseModule.class)
public interface BaseComponent {
 public Person providePerson();
}

//Component1.java
@PerActivity
//@Singleton
//因为依赖（dependencies）的BaseComponent中用到了@Singleton，所以这个Component就不能再用了，否则会编译错误，为什么这么设计还不是很清楚
@Component(modules = Module1.class,dependencies = BaseComponent.class)
public interface Component1 {
 void inject(TestScopeActivity1 simpleActivity);
}

//Component2.java
@PerActivity
//@Singleton 为什么不能用？原理同上
@Component(modules = Module2.class,dependencies = BaseComponent.class)
public interface Component2 {
 void inject(TestScopeActivity2 simpleActivity);
}

//MyApplication.java
public class MyApplication extends Application {

 private static BaseComponent baseComponent;

 @Override
 public void onCreate() {
 super.onCreate();
 baseComponent = DaggerBaseComponent.builder().build();
 }

 public static BaseComponent getBaseComponent() {
 return baseComponent;
 }
}

//TestScopeActivity1.java
public class TestScopeActivity1 extends Activity {

 @Inject
 Person p = null;

 @Override
 protected void onCreate(Bundle savedInstanceStatE) {
 super.onCreate(savedInstanceStatE);
 setContentView(R.layout.activity_main);
 DaggerComponent1.builder().baseComponent(MyApplication.getBaseComponent()).build().inject(this);
 TextView textView = findViewById(R.id.textView);
 textView.setText(p.toString());
 textView.setOnClickListener(new View.onClickListener() {
  @Override
  public void onClick(View v) {
  startActivity(new Intent(TestScopeActivity1.this,TestScopeActivity2.class));
  }
 });
 }
}

//TestScopeActivity2.java
public class TestScopeActivity2 extends Activity {

 @Inject
 Person p = null;

 @Override
 protected void onCreate(Bundle savedInstanceStatE) {
 super.onCreate(savedInstanceStatE);
 setContentView(R.layout.activity_main);
 DaggerComponent2.builder().baseComponent(MyApplication.getBaseComponent()).build().inject(this);
 TextView textView = findViewById(R.id.textView);
 textView.setText(p.toString());
 }
}